(1) Field of the Invention
This invention relates to a preparation for producing a material used to restore a mineralised substance, in particular in the dental field.
(2) Prior Art
In the dental field, the crown is restored so as to overcome, inter alia, the loss of substance associated with the destruction of dental tissue by caries or resulting from a shock.
Until now, the restoration of “impaired” teeth accounts for 75 to 80% of dental treatments (P. Hescot et al.; 1996; Programme International de Recherche de l'Organisation Mondiale de la Santé sur les déterminants et la santébucco-dentaire; Association Dentaire Française).
Currently, dental restoration uses essentially two types of materials for restoration to avoid the need for involvement of a prosthesis laboratory.
The oldest material, used since the 19th Century, is silver amalgam.
Very widely used, its placement by the practitioner is very simple and its mechanical strength has long been demonstrated. Moreover, the average lifespan of an amalgam filling is estimated to be 14 years.
However, silver amalgam has two major disadvantages.
The first disadvantage is associated with the presence of 40 to 50% mercury in its composition. The possible danger of the release of mercury in the saliva and the environment when positioning the material, as well as in wastewater when it is removed, has led to a gradual rejection of the use of this type of material.
The second disadvantage is associated with the inaesthetic metal appearance of fillings made with silver amalgam.
To overcome the disadvantages of the presence of mercury and the inaesthetic appearance of silver amalgams, a second type of restoration material has been developed. It consists of composite resins.
The composite resins are formed by a mixture of organic resin and mineral fillers, which is specifically treated with a product that ensures the binding of the resin to the mineral fillers, without any mercury.
Originally intended for the treatment of anterior teeth, because they satisfy the patients' aesthetic requirements, they are also used for the restoration of posterior teeth.
However, it is noted that the fillings produced with these composite resins have an estimated average lifespan of 7 years, that is half that of the silver amalgam fillings.
This short lifespan of composite resin fillings can be explained by the phenomenon of contraction of the composite resin which occurs during the setting reaction of the composite resins and which no longer provides an adequate marginal seal during the polymerisation reaction, which constitutes a major problem in the use of such resins.
Until now, and in spite of numerous attempts to improve the components of composite resins as well as the associated techniques for use, no composite resin has an adequate marginal seal, in particular in the areas where there is little or no enamel.
In addition, the environmental and aesthetic advantages of composite resins lead to lower spending in terms of public health and savings for the health care budget.
Therefore, there is a real need to have a restoration material for dental reconstitution that offers a compromise between the advantages of silver amalgams, in particular in terms of longevity and mechanical strength, and those of composite resins, namely the absence of mercury and the aesthetic appearance of the filling.